I am putting together my solar charging
system at the moment. I have two Kyocera
125 Watt panels
and plan on adding two more. Two will be mounted on foldable stanchion mounts and two will be mounted on the cabin
top of my Prout.
At this point I am planning to series two panels
and run them into an MPPT
controller. I will add the two additional panels later. If I go with one charge controller I will need to get a larger model, such as the Outback MX60 or Blue Sky SB50, to support the maximum current
. Another option I was considering was to buy a 25 amp controller such as a Blue Sky SB2000. As I add another set of panels I could add a second controller and wire the outputs in parallel to the batteries.
Pros and cons...
One piece of equipment
to mount and one set of wires to the batteries. (not a big deal in my case).
Perhaps a little bit cheaper than two smaller controllers (but not much).
No concern about the controllers fighting each other**.
No redundancy or backup. Loose the controller and loose all of the solar
Less efficiency: If the cells are partially shaded then the reduced current
from one panel will drag down the other in series. This in turn could affect the MPPT
unit to adjust the panels in parallel and reduce the overall efficiency.
redundancy. Even if I loose one controller I would still have half of my panels working for me.
Each controller can adjust its MPPT point to the highest efficiency for its panels.
I can mix panels sizes and types since the 125W panels have been replaced with 130W panels. I could put my two current panels on one controller and place the new panels on their new controller so each MPPT controller could adjust separately.
More Equipment and more wires to mount. (Not too big of a deal)
Slightly higher cost.
The charge controller outputs could interfere with each other**. (I am a little fuzzy on this).
**Am I on the right track here? If I have two controllers feeding the same 550 AH battery
bank could one be in the bulk charge mode and cause the other to think it should be in float mode?
Any feedback will be helpful.